The
Cosby Sweater, the wonderfully garish "knit woolen thing that look
like the sheep were different colors or fell in some paint" (as Cosby
himself once said), is a cultural icon (it even has its
own Tumblr blog).

Lemire says that Cosby often strayed from the script, following his
gut if he thought it might get a better laugh. “It was incredible
and it came out of nowhere, and the director knew to grab that.”
As a result, the show often relied on close-up shots of Cosby to capture
such moments of improvised humor. However, tight shots like these caused
problems when matching the scenes from two different takes, as a slight
difference in costume positioning would become a glaring mistake.

“Usually you don’t do close-ups on TV, and that’s
why we started using sweaters,” says Lemire. “As our bodies
move around, the clothes are going to shift between the first and second
take. If you have a jacket on, and the shirt collar’s in one spot,
it’s going to slide off a little on one side or the other, or
it might do something else that didn’t match. [Director Jay Sandrich]
was a real stickler for things matching, so we just did the sweater
thing. I actually sewed his shirts to the sweaters so that nothing moved.”